Materials and methods for pressure and temperature sensors at cryogenic temperatures

Claim 2

A capacitive pressure sensing device for use at cryogenic temperatures comprising first and second electrodes having a layer of dielectric material therebetween, said dielectric material consisting essentially of a pyrochlore ferroelectric ceramic having the formula: (Cd.sub.1-x M.sub.x).sub.2 (Nb.sub.1-y M'.sub.y).sub.2 O.sub.7, where x and y are numbers in the range of from 0 to 1, M is selected from the group consisting of Pb, Ca, Sr, Ba, and mixtures thereof, and M' is selected from the group consisting of Ta, Sb, and mixtures thereof.

Claim 3

The capacitive pressure sensing device of claim 1 in which M, M', x, and y are chosen such that the dielectric constant of said ceramic is essentially temperature independent below 15 K.

Claim 4

The capacitive pressure sensing device of claim 1 in which M is Pb and M' is Ta.

Claim 5

The capacitive pressure sensing device of claim 3 in which x is 0.2 and y is 0.8.

Claim 6

The capacitive pressure sensing device of claim 3 in which x is 0.6 and y is 0.5.

Claim 7

The capacitive pressure sensing device of claim 3 in which x is 0.5 and y is 0.5.

Claim 8

A capacitive temperature sensing device for use at cryogenic temperatures comprising first and second electrodes having a layer of dielectric material therebetween, said dielectric material consisting essentially of a pyrochlore ferroelectric ceramic having the formula: (Cd.sub.1-x M.sub.x).sub.2 (Nb.sub.1-y M'.sub.y).sub.2 O.sub.7, where x and y are numbers in the range of from 0 to 1, M is selected from the group consisting of Pb, Ca, Sr, Ba, and mixtures thereof, and M' is selected from the group consisting of Ta, Sb, and mixtures thereof.

Claim 9

A capacitive temperature sensing device for use at cryogenic temperatures comprising first and second electrodes having a layer of dielectric material therebetween, said dielectric material consisting essentially of a pyrochlore ferroelectric ceramic having the formula: (Cd.sub.1-x M.sub.x).sub.2 (Nb.sub.1-y M'.sub.y).sub.2 O.sub.7, where x and y are numbers in the range of from 0 to 1, M is selected from the group consisting of Pb, Ca, Sr, Ba, and mixtures thereof, and M' is selected from the group consisting of Ta, Sb, and mixtures thereof.

Claim 10

The capacitive temperature sensing device of claim 7 in which M, M', x and y are chosen such that the dielectric constant of said ceramic varies proportionally with temperature in the range of 0 to 15 K.

Claim 11

The capacitive temperature sensing device of claim 7 in which M is Pb and M' is Ta.

Claim 12

The capacitive temperature sensing device of claim 9 in which x is 0.1 and y is 0.

Claim 13

A combination pressure and temperature sensing device for use at cryogenic temperatures comprising first and second pairs of electrodes having first and second layers of dielectric material therebetween, respectively, said dielectric material consisting essentially of pyrochlore ferroelectric ceramic having the formula: (Cd.sub.1-x M.sub.x).sub.2 (Nb.sub.1-y M'.sub.y).sub.2 O.sub.7, wherein x and y are numbers in the range of from 0 to 1, M is selected from the group consisting of Pb, Ca, Sr, Ba, and mixtures thereof, and M' is selected from the group consisting of Ta, Sb, and mixtures thereof, said first pair of electrodes and said first layer of dielectric material therebetween forming the pressure sensing portion of said device and wherein M, M', x and y are chosen such that the dielectric constant of said first layer of dielectric material is essentially temperature independent below 15 K., and said second pair of electrodes and said second layer of dielectric material therebetween forming the temperature sensing portion of said device, and wherein M, M', x, and y are chosen such that the dielectric constant of said second layer of dielectric material varies proportionally with temperature in the range of 0 to 15 K.

Claim 14

A combination pressure and temperature sensing device for use at cryogenic temperatures comprising first and second pairs of electrodes having first and second layers of dielectric material therebetween, respectively, said dielectric material consisting essentially of pyrochlore ferroelectric ceramic having the formula: (Cd.sub.1-x M.sub.x).sub.2 (Nb.sub.1-y M'.sub.y).sub.2 O.sub.7, wherein x and y are numbers in the range of from 0 to 1, M is selected from the group consisting of Pb, Ca, Sr, Ba, and mixtures thereof, and M' is selected from the group consisting of Ta, Sb, and mixtures thereof, said first pair of electrodes and said first layer of dielectric material therebetween forming the pressure sensing portion of said device and wherein M, M', x and y are chosen such that the dielectric constant of said first layer of dielectric material is essentially temperature independent below 15 K., and said second pair of electrodes and said second layer of dielectric material therebetween forming the temperature sensing portion of said device, and wherein M, M', x, and y are chosen such that the dielectric constant of said second layer of dielectric material varies proportionally with temperature in the range of 0 to 15 K.

Claim 15

The combination pressure and temperature sensing device of claim 11 in which M is Pb and M' is Ta.

Claim 16

The combination pressure and temperature sensing device of claim 12 in which for said first layer of dielectric material, x is 0.6 and y is 0.5.

Claim 17

The combination pressure and temperature sensing device of claim 12 in which for said second layer of dielectric material, x is 0.1 and y is 0.